In general, chocolate is produced by appropriately mixing cacao mass, cocoa, cacao butter, a cacao butter substitute, a sweetener, milk powder and the like, and subjecting the resulting chocolate mix to rolling, conching and tempering. In chocolate thus obtained, there is a problem that blooming is often caused during storage, which lowers the commercial value thereof. Blooming is divided into fat blooming caused by unstable crystals of fats and oils, and sugar blooming caused by recrystallization of sugar. Particularly, the former fat blooming is frequently caused.
Tempering is effected from the viewpoint of transformation of a crystal form of fats and oils in chocolate into a stable one to prevent fat blooming. When tempering is insufficient, fat blooming may be caused under various conditions and, in excessive cases, even release from a mold becomes difficult. Thus, tempering is an important step in chocolate production. However, even if sufficient tempering is effected, it is very difficult to prevent blooming, when chocolate is exposed to a high temperature such as about the melting point of a product at which it loses its hardness for a certain period of time (e.g., exposure to sunlight in summer).
Further, there are respective characteristic optimum conditions according to a particular formulation of fats and oils in chocolate, cooling rate and the like, and the optimum tempering conditions can not be always readily found out. For example, almost all refrigerators used for tempering have relatively little versatility, and are assembled so that they are adapted to specific cooling rates. Accordingly, the degree of tempering of chocolate should be adjusted based on a particular type of a refrigerator to be used, and it is often experienced that a particular tempering style should be preliminarily found out (M.G. Reade, The Manufacture Confectioner/January 1985).
Thus, there are various methods for tempering. However, in industrial practice, tempering usually contains at least one step for force-cooling a molten fatty composition, i.e., a molten chocolate mix, and at least one step for reheating it (e.g., cf. "Seika Jiten" page 459, October, 1981, published by Asakura Shoten). It is clear that the loss of energy becomes generally greater, when both cooling and subsequent heating are effected in a single apparatus. Therefore, it is necessary to install two kinds of apparatuses for cooling and heating (Japanese Pat. Kokai No. 61-40750).
On the other hand, there is a tendency to omit such a troublesome tempering operation if possible and, for this purpose, it has been proposed to use a hard butter having a high elaidin content, a laurin type hard butter, a hard butter wherein the fatty acid arrangement is randomized by interesterification or the like. However, when using these hard butter, a large amount of cacao butter can hardly be used and therefore there is limitation to provide a resulting chocolate product with desired taste and flavor of cacao butter.
Further, in order to prevent fat blooming, various hard butter compositions and fatty additives have been proposed.
For example, Japanese Pat. Kokoku Nos. 46-26823 and 46-26824 disclose a fat blooming inhibitor which is a fractionated oil having an iodine value of 33 to 55, a melting point of 30.degree. to 70.degree. C., a specific fatty acid composition and SCI characteristics obtained by interesterification of a hardened oil containing a main acid moiety of fatty acids having 20 to 24 carbon atoms such as a hardened rapeseed oil, and a hardened oil containing a main acid moiety of fatty acids having 16 to 18 carbon atoms such as a hardened tallow, or a hardened oil containing a main acid moiety of fatty acids having 12 to 14 carbon atoms such as a hardened laurin oil (e.g., palm kernel oil); and fractionation of the resulting product. Japanese Pat. Kokoku No. 47-16926 discloses a process for production of chocolate using a similar fractionated oil to prevent fat blooming. Japanese Pat. Kokai No. 58-198245 discloses a fat blooming inhibitor which is a fat containing as the main acid moiety 20 to 60% by weight of behenic acid. Japanese Pat. Kokoku No. 60-24749 discloses a process for producing a trans-acid type hard butter having a specific fatty acid composition consisting of elaidic acid, palmitic acid, behenic acid and other fatty acids, wherein the fatty acid residues are randomly distributed. European Pat. Application Publication No. 0196780 (A2) discloses a fat blooming inhibitor which is a mixed acid triglyceride having as the main acid moiety 15 to 70% by weight of saturated fatty acids having 20 to 24 carbon atoms and 20 to 60% by weight of unsaturated fatty acids having 16 to 22 carbon atoms. European Pat. Application Publication No. 0227364 (A2) discloses a hard butter composition having antiblooming property which comprises as a main ingredient a .beta.- unsaturated- .alpha.,.alpha.'- disaturated triglyceride, constituent saturated fatty acids of which contain at least 4% by weight of one or plurality of fatty acids selected from the group consisting of behenic acid, lignoceric acid, cerotic acid and arachidic acid, provided that the amount of arachidic acid is less than 4% by weight based on the total weight of the constituent saturated fatty acids.